The present invention relates, in general, to a high intensity discharge lamp (hereinafter called "HID") control circuit, and more particularly to a protection circuit for a stabilizer in such a discharge lamp control circuit. Such a lamp may include a discharge tube activated by a main electrode, not necessarily having a pre-heated electrode, or may include a high-luminance discharge lamp such as a high pressure sodium lamp, a high pressure mercury lamp, or a metal halide lamp.
In recent times, HID devices have employed stabilizers which operate by means of either voltage-ignition or current-ignition but those stabilizers have defects such as high power consumption, overheating of power lines, and heavy weight. Moreover, HID devices require a delay time between the switching off of the lamp and its re-lighting, because such devices use a discharge tube which becomes heated when the lights are turned on and which cools when the lights are turned off, and lighting the lamp at a time before the discharge tube has sufficiently cooled, as in an instantaneous re-lighting, can destroy the system due to overheating. An attempt to protect such systems from such overheating is described in U.S. Pat. No. 5,051,661, wherein protection was accomplished by blocking the power to the lighting circuit from a power supply. However, once the protection circuit of this patent disables the power supply, the user must manually turn off a switch controlling the circuit, and then turn it back on to make the system operational and to activate the lighting circuit. Such an inconvenience is a barrier to utilizing such lamps, particularly in cases where the HID is used for an outdoor lamp.